Data Acquisition Scheme for Nuclear Physics Experiments

The data acquistion set up for nuclear physics experiments at ELBE is based on a mixed synchronized readout of various digitizers in different form factors (crates). The central processor unit (CES CPU) resides in a VME crate and runs the readout software MBS [1] developped at GSI. The operating system is LynxOS. Readout procedures for each component had been developped and tested, and a simple CAMAC ESONE library has been implemented. CAMAC readout is performed using CAMAC crate controllers (WIENER CC32) connected to the VME CAMAC branch driver (WIENER VC32) via standard SCSI cables.

Asynchronous readout for single spectra and scaler data:

Data exchange with accelerator control:

Several data exchange paths have been set up to exchange data between the user experiment and the accelerator control system. Since, the nuclear physics setup is based on a real-time unix system running on PowerPC platforms, the whole accelerator works with Siemens Simatic and Windows-based Intel systems. Therefore, the data exchange is done by TCP/IP communication stacks via the local ethernet connections. Right now, three data paths are used for various purposes:

OPC data exchange from the accelerator control to the user experiment. Multiple parameters of the accelerator are included into the online data acquisition flow (electron gun current, micro-pulse and macro-pulse repetition rates, acceleration gradients in the accelerator, electron beam dump currents, radiator target position, beam shutter and hardener position, status of the interlock system, etc.)